In the modern society glutted with electronic technologies, the applications of printing devices can be found everywhere in our daily lives. The barcode machine is broadly applied to various products and payment bills, and even for the logistics control of companies. In general, the barcode printers usually provide the paper, the carbon ribbon, or the color ribbon arranged by the way of a roll. The roll is usually arranged in the barcode printer by locating both ends of the roll in the positioning trenches or assembling a clamp to fix the roll directly.
The traditional positioning device is usually provided for a roll of a certain dimension. That is, the rolls of different dimensions cannot be fixed at the positioning device. if the roll is not properly fixed or becomes lighter because of the reduction of carrier (e.g. paper) on the roll, the pulling action on the carrier may result in the unwanted movements or shaking on the roll to generate deviation of printing position to reduce printing quality. For a barcode machine, such drawback will result in the recognition problem.